Discontinued Operations and Assets Held For Sale - Schedule of Earnings (Loss) on Discontinued Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Discontinued Operations And Disposal Groups [Abstract]
Total revenues			$ 121
Impairments	$ (1,042)	$ (4,248)	(5,746)
Other operating income	3,180	3,012	3,218
Earnings (loss) from operating activities	2,138	(1,236)	(2,407)
(Loss) gains from dispositions of real estate		(178)	339
Earnings (loss) from discontinued operations	$ 2,138	$ (1,414)	$ (2,068)